Control apparatus



y 1940- P. B. LENARD 2,202,294

CONTROL APPARATUS Filed Aug. 5, 1936 3 Sheets-Sheet 1 INVENTOR LONAQD BYWflJ-TM ATTORNEY y 8, 1940. P, B. LEONARD 2,202,294

CONTROL APPARATUS Filed Aug. 5, 1936 3 Sheets-Sheet 2 INVENTOR 4043,450A/AQ0 BY W 4 ATTORNEY May 28, 1940. P. B LEONARD 2,202,294

I CONTROL APPARATUS Filed Aug. 5, 1936 3 Sheets-Sheet 3 57.]1. 1 '9. Z5. INVENTOR Pwz. ELEM/App W64}? ATTORNEY Patented May 28, '1940 CONTROLAPPARATUS Paul B. Leonard, Columbus, 0hio, assignor to RancoIncorporated, Columbus, Ohio, a corporation of Ohio Application August5, 1936, Serial No. 94,411

24 Claims.

My present invention relates to switches and more particularly to anelectric switch.

One of the objects of my invention is to provide a switch in which thebreak, or separation, between the contacts is relatively wide inrelation to the movement of the actuating mechanism.

Another object is to provide a constant, high, contact pressure at theinstant before separation of the contacts, to eliminate chattering andsubsequent arcing of the contacts.

A further object is to provide a snap action device that operatesthrough the resultant force components of opposing springs to producepositive snap action without the usual graduating tendency.

Other and further objects and advantages will be apparent from thefollowing description, reference being had to the accompanying drawingswherein a preferred form of embodiment of the present invention isclearly shown.

Fig. 1 is a side elevational view of the switch;

Fig. 2 is a front elevational view of the switch having the housing cutaway and the adjustment spring removed;

Fig. 3 is an enlarged front view of the snap mechanism;

Fig. 4 is an enlarged side view of the snap mechanism with the contactsin the closed position;

Fig. 5 is a similar view of Fig. 4 with the contacts in the openposition;

Fig. 6 is a diagrammatic view of the mechanism in the closed positionwith spring 2| removed;

Fig. '7 is a view similar to Fig. 6 with spring 22 removed and spring 2|in place;

Fig. 8 is a diagrammatic view of the mechanism with spring 2| removedand shown in the position at the instant before the separation of thecontacts;

Fig. 9 is a similar view to Fig. 8 with spring 22 removed and spring 2|in place;

Fig. 10 is a diagrammatic view of the mechanism with spring 2| removedand with the contacts in an open position, and,

Fig. 11 is a similar vir to Fig. 10 with spring 22 removed and spring 2|in position.

The embodiment of the switch as shown in the (01. zoo-gas) upper end,which is clamped to the base plate I! by a removable collar I, held inplace by screws 3|. This collar I does not clamp the housing I! sotightly that it can not be turned manually, but neither is there anyappreciable end play. 5 This attachment allows rotation of the housingl8, together with the enclosed bellows ll, without changing the relativeposition of the bellows IT to the associated mechanism. An elbow IE orother convenient means is used to engageably at- 10 tach the bellows I'Ito the pressure system, which may be an air or steam line, or other typeof conduit, or the bellows may be connected to a bulb and tube as isfamiliarly used in refrigeration controls. A change of pressure withinthe bell5 lows l1 acts to vary its length, which variation istransmitted to the snap mechanism by a push rod I5.

Rod l5 acts against a lever 84, which is U- shaped at the lower end, atthe bearing point 32. 20 The bearing 32 is formed by a depression in thelever M to receive the conical end of the rod I5. The lever M is theactuating lever for the switch mechanism and is pivoted at its lower endon the knife edge bearing of a rod 23, which in cross sec- 5 tionresembles a sector of a circle. The rod 23 is set in apertures 26 formedin the bracket 5. These apertures 26 are of similar shape to the crosssection of the rod 23. The bracket 5 is sub stantially U-shaped at itslower end and is perso manently attached to the base plate IS. Thebearings 36 in the actuating lever M are also in the shape of a sectorof a circle, but with a greater degree are than is used in the bracket5. This additional arc allows the necessary space for the 5 movement ofthe lever M with respect to the bearing rod 23. The lever I4 is heldtightly against the push rod 5 by the tension of a spring I3, attachedto the lever M at 3'! and adjustable through the screw |2 which turns ina plate 33. It will be noted that the plate 33 is provided with aprojection 34 that is slidably engaged with a slot 35 in the frame 20.This engagement allows longitudinal adjustment of the plate 33 andattached spring l3 by the action of the screw |2, without the plate 33turning, or otherwise becoming disengaged from the spring l3. The screwadjustment l2 varies the tension of the spring on the actuating lever l4thereby changing the pressure exerted through the associated pin I5 onthe bellows I1. This change in pressure varies the adjustment of thedevice. The projection 34 of plate 33 extends through frame 20, and isused as an indicator for the setting of the spring I3. 66

The lever |4 cooperates at its upper end with a lever, or movablecontact element ii, that carries the movable contacts it loosely set inan insulating memberil, attached to the contact element The movableelement it engages, on closing, with the fixed contact member 8, whichmay be connected to the electrical circuit by associated lugs l. Thecontact 8 is set in insulating .material 2 which is secured to thebracket 5 by the member 24. The lower end of movable element N forms aknife edge which is pivoted on the lever M at the bearing M. Thisconstruction may be more clearly seen in the enlarged views shown inFigs. 3, 4 and 5, where the relationship of parts is well illustrated.

The upper or free end of lever i4 is connected to the free end of atoggle, or flipper member 8 by the spring 2|. its upper, pivoted end ina knife edge or V-shaped bearing 28 which is formed in the fixed bracket5. The lever II is also connected to the free end of the toggle 6 by thespring 22. The movement of the free end of the toggle his limited andadjustable in both directions by the screw stops 3 and 4. Stop 3 ismounted on the lever l4; this particular construction is not limiting,but merely the most obvious method of manufacture. Stop 4 is screwedthrough the member 24 which is associated with the support bracket 5 byrivets. The screw 3 (see Fig. 3) is engaged through the threaded hole 3in lever M. This hole 3' is in the elongated spring slot which providesfor a tight thread at all times without the use of a lock nut. Screw 4is similarly engaged. These two stops 3 and 4 furnish the differentialrange adjustment for the instrument. It is evident that by limiting thefree movement of the toggle S that the differential of the device may bevaried within any reasonable limits.

The pivotal mounting of member H on lever I4 is important to the successof my invention. As the lever l4 shifts in position, as occasioned bymovement of the bellows ill, the fulcrum 21 for lever moves towards thedead center position of the toggle member t and the movable element I I.This action tends to reduce the bellows movement necessary to secureoperation of the snap mechanism.

The pivotal mounting of lever ii on lever M has another advantage froman electrical standpoint. As the lever i 4 moves, its fulcrum point 21also moves, but since this fulcrum point 21 is not on the same center asthe fulcrum point 36, of the lever H, the fulcrum 27 described an are asit moves. This path of movement rubs, or wipes the contacts Ml againstthe contacts 8 which keep the surfaces of the contacts from stickingjust before the separation of the contacts.

At the start of the closing cycle, the switch is in the position shownin Fig. 5 with the projection 29 serving as a stop for the outwardmovement of lever As lever l4 moves to close the switch, due to adecrease in bellows pressure, the stop 29 on the lever 04 moves leverclockwise so that it approaches its dead center position. This movementsimultaneously displaces the spring 2| that is attached to the lever l4and to the flipper 6. When spring 2| and flipper 6 pass the dead centerposition, the spring 2| snaps the flipper 6 from stop 3 to stop 4; thismovement also carries the spring 22 to the right of the dead centerposition for lever i, and lever II will snap from stop 29 to thecontacts 8 and the switch will be closed. This snap ac- The toggle 6 issupported at a tion of lever ii and flipper 6 is substantiallyinstantaneous. At practically the same instant lever M will followthrough, due to the change in pull of spring 2| caused by the change inthe position of flipper 6 from stop 3 to stop 4, to hit against thelever It and greatly increase the closing contact pressure.

On opening the device, the spring 2| overcomes the spring 22 to snap thetoggle open before the lever |4 contacts the projection 25 on leverneither is the point 29 in contact with the lever II. This allows foradditional movement of free travel on the separation of the contacts.The projection 25 is placed on lever II to engage lever M if for anyunforseen reason the contacts do not separate. This is an added measureof safety. In this event, the direct contact of the levers H and I4cooperate to force the separation of the contacts. It will be noted thatin this position the pressure within the bellows is acting directly onthe lever through lever l4 without any intervening members beingactuated. Similarly, on the closing of the device, the actuating member|4 through its integral projection 28, bears or acts directly on themovable member H. Thus, during closing of the switch, the action isdirect from the bellows through lever N to the movable member H withoutthe intervening action of the toggle mechanism, which does not come intooperation until the movable member passes its dead center position. Atthis point the flipper 6 is snapped through dead center to snap themovable member ii to the closed position. It will be noted that thecontact separation is relatively small at the instant before the closureof the contacts, whereas the contact separation is relatively great onthe opening. This relation between the contacts is very desirable as awide brea prevents arcing, etc, when the switch opens.

The leverage ratio of the actuating lever I4 is relatively high and maybe utilized due to the construction of the switch, which does not have agraduating tendency at the instant before separation of the contacts butmaintains the high contact pressure until the contacts are separated bythe snap mechanism. Therefore, the movement of the upper end of theactuating lever I4 is relatively large compared to the movement of thelever or bellows end of the lever. Thus for a short bellows movement awide separation of the contacts may be obtained.

The snap action of the device is acquired by the action of the two snapsprings 2| and 22 cooperating with the movable contact lever H, theactuating lever l4, and the flipper 5. The spring 22 connects themovable contact member II to the flipper member 6. The tension of thespring 22, through its horizontal component of force, tends to press themovable contacts ID to the fixed contacts 8, in the closed position ofthe switch. The spring 2| connects the flipper 6 to the actuating memberM. The spring 2| is preferably heavier than the spring 22.

Figs 6 to 11, inclusive, illustrate diagrammatically the action of thesprings and toggles as the switch is actuated for separation of thecontacts. In Fig. 6 the contacts are shown in closed position, and forthe sake of clarity, spring 2| is removed, since springs 2| and 22superimpose on one another in the side view of the switch. Fig. '7,therefore, is an identical view to Fig. 6, but showing the spring 2| andomitting spring 22. Figs 8 and 9 are similar views at the instant beforeseparation of the contacts.

As the actuating member It moves counter clockwise from the positionshown in Figs. 6 and 7, due to the expansion of the bellows, itdisplaces the spring 2| from the position shown in Fig. 7 to theposition shown in Fig. 9. Although at the time lever l4 moves the spring2| beyond its dead center position, with respect to flipper 6, theflipper 6 is not' displaced at that instant due to the opposing force ofspring 22. At the instant that the horizontal component of spring 2|exceeds the horizontal component of spring 22, the flipper will besnapped from the stop 4 to stop 3. Figs 8 and 9 show the position of theelements at the instant that the force of spring 2| is equal to theforce ofspring 22. At the instant that the force of spring 2| overcomesthe force of spring 22, the flipper 6 is snapped through its own deadcenter and the elements are moved from the position shown in Figs. 8 and9 to the position shown in Figs. 10 and 11. Let us assume that theswitch is in the position shown in Figs. 6 and '7 and, for example,spring 22 has a horizontal force component. of ten pounds, the spring 2|having a horizontal force component of five pounds in the oppositedirection. The resultant force component tending to keep the flipper 6in its original position against stop 4, will be flve pounds. As thespring 2| is displaced to the position shown in Fig. 9, its horizontalforce component increases to a point where it is ten pounds in theopposite direction of the ten pound component of spring 22. This gives aresultant force of zero of the flippers against stop 4.

The instant that the component of force of spring 2| exceeds ten pounds,it will snap the flipper 6 through the dead center position of thelatter. Due to this movement of flipper 5, the angularity between theflipper 6 and the spring 2| is constantly increasing to produce acorrespondingly constant increase in the horizontal force component ofthe spring 2|. This constantly increasing component of force of spring2| insures contact separation, which separation is constantly increasingin speed from the very start to the completion thereof.

The contact pressure of contact ID on contact 8 is unchanged until snapaction occurs. Fig. 8 illustrates very clearly why the contacts have amaximum pressure even at the instant before separation, for it will benoted that the horizontal component force of spring 22 at its upper endas exerted on contacts I is unchanged during the movement of spring 2|.

The present switch presents a, device with positive spring action toassure constant, high, contact pressures and positive make and break ofthe points, thus providing perfect switch operation, entirely devoid ofchattering or arcing. The movable contacts l0, due to their looseengagement with the insulating member 9 having a slight wiping action onclosing. This is also advantageous for perfect operation.

My present invention has numerous distinct advantages over snap actiondevices of theusual design. It is a well known fact that switches andthe like, having small differentials in their operating ranges usuallyhave a very limited movement between the switch points.

My invention differs from the usual switch in that compensatingadjustments, automatic in character, are provided, that not only allow avery small differential range, but also allow an exceptional break, ormovement of the points.

This relatively large break is made possible by the lost motion andmovable fulcrum features'of the invention. In order that this lostmotion," which allows wider separation of contacts, does not increasethe difierential, the compensating movable fulcrum is provided for themovable contact member. The movement of the fulcrum points disposes thelever in position to snap with no additional travel of the bellows. Inother words the displacement of the fulcrum, for the movable member,takes up the lost motion.

Although the description of my invention is d rected to electricalswitches, it is to be understood that the principles involved should notbe limited to use in these specific devices. It is evident that thebenefits derived from the described mechanism, namely, a relativelylarge movement of the snap member for a relatively small movement of theactuating medium, would be well adapted for use in a number of devicescompletely divorced from electrical switches. The inherent advantagesinvolved would, for example, be well employed in valves of the snapaction type, for use with fluids of various kinds, whether such valvesor mechanisms are actuated by the described bellows or by such otherwell known mediums as bimetal, rod and tube expansion elements, etc.

In fact, the described mechanism will be extremely useful in any type ofdevice where a strong, definite action or movement is required under lowdifferential conditions.

While the form of embodiment of the present invention as hereindisclosed constitutes a preferred form, it is to be understood thatother forms might be adopted, all coming within the scope of the claimswhich follow.

I claim as my invention:

1. In a snap action device, a movable element, a flipper fulcrumed atone end, a spring connecting the movable element and the flipper, anactuating member, a spring connecting the actuating member to theflipper, stop means disposed to contact the free end of the flipper andmeans for moving the actuating member.

2. hi a snap acting device, relatively fixed and movable elements, asnap member, an elas tic means cooperating with said movable element andsaid snap member, an actuating member, a resilient means connecting saidactuating member and snap member, said snap member, resilient means andactuating member having a dead center position, said actuating memberbeing so disposed in relation to the snap member that when the deadcenter position of the snap member is passed that both the elastic meansand the resilient means react cooperatively to move the movable element.

3. A snap acting device comprising, a movable element to be actuated, aflipper, a spring connecting the movable element and the flipper, anactuating member, a spring connecting the actuating member to saidflipper and means for moving the actuating member.

4. A snap acting device comprising a movable element to be actuated; aflipper fulcrumed at one end; a spring having one end thereof connectedwith the free end of the flipper and having the other end thereofconnlected with the element, said spring, flipper and elel0 ment havinga dead center position; an actuating member; a spring connected with theactuating member and with the free end of said flipper, said lastspring, actuating member and flipper having a dead center position andsaid i last spring being adapted to move the flipper beyond its deadcenter position with respect to the first spring, flipper and firstelement when the second spring is moved beyond its dead cen ter positionrelative to the flipper and actuating member; and means for moving theactuating member.

5. In a snap acting device, a movable element to be actuated, a flipperfulcrumed at one end; a spring having one end connected to the free endof the flipper and having the other end connected with the element, saidspring, flipper and element having a dead center position, an actuatingmember carrying a fulcrum for said movable element; a second springconnected with the actuating member and flipper, said flipper, actuatingmember and spring having a dead center position, said actuating memberbeing adapted to move the movable element and the second spring towardthe dead center positions; and means for moving the actuating member.

6. In a snap acting device, a movable element to be actuated; a flipperfulcrumed at one end; a spring having one end connected to the free endof the flipper and having the other end connected with the element; saidspring, flipper and element having a dead center position; an actuatingmember carrying a fulcrum for said movable element; a spring connectedwith the actuating member and with the free end of said flipper, saidlast spring, actuating member and flipper having a dead center position,said actuating member being adapted to move the movable element towardits dead center position, said last named spring being adapted to movethe flipper beyond its dead center position with respect to the firstspring, flipper and first element when the second spring is moved beyondits dead center position relative to the flipper and actuating member;and means for moving the actuating member.

'7. In a snap acting device, a movable element to be actuated; a flipperfulcrumed at one end; a spring having one end connected to the free endof the flipper and having the other end connected with the element; saidspring, flipper and element having a dead center position; an actuatingmember carrying a fulcrum for said movable element; a spring connectedwith the actuating member and with the free end of said flipper, saidlast spring, actuating member and flipper having a dead center position,said actuating member being adapted to move the movable element towardits dead center position, said last named spring being adapted to movethe flipper beyond its dead center position with respect to the firstspring, flipper and first element When the second spring is moved beyondits dead center position relative to the flipper and actuating member;and means for moving the actuating member.

8. In a snap acting device, relatively stationary and movable elementsto be controlled; an actuating member, said movable element adapted I tobe limited in its movement in one direction by the stationary elementand adapted to be limited in its movement in the other direction by theactuating member, said movable element and actuating member being spacedfrom one another for free travel of the movable element; a flipper; aspring connected with the flipper and the movable element, said secondspring, flipper and element having a dead center position, said springbeing adapted to snap actuate the movable aeoaaoe element when thespring, flipper, and movable element are moved beyond their dead centerposition; and a second spring connecting the flipper and the actuatingmember, said second spring, flipper and element having a dead centerposition, said second spring being adapted to snap actuate the flipperbeyond the dead center position of said first spring, flipper andmovable element when the actuating member moves beyond its dead centerposition with respect to the flipper and second spring.

9. In a snap action device, a plurality of levers, yielding meansinterconnecting one of said levers to each of two other levers, saidyielding means having unequal and opposing force components, means toactuate one of said second levers to increase the force components ofone of said means whereby snap action occurs when the increasing forcecomponent exceeds the stationary force component of the other means.

10. In a snap acting device, a plurality of pivoted elements havingtheir free ends disposed oppositely from one another, a springconnecting said elements for urging the free ends in one direction whenthe spring is in one position, a second spring connected to one of saidelements for moving the elements in the opposite direction, and meansfor increasing the force of the second mentioned spring on the oneelement for overcoming the force of the first mentioned spring on theelement.

11. In a snap acting device, a movable element, resilient means forurging the element in a certain direction, said element and means beingso disposed with respect to one another that the component of force ofsaid means acting upon the element decreases when the element is movedin opposition to said means, a spring tending to move said element in adirection opposite the said certain direction, and mean for moving thespring to increase the force of said spring to a point at which itovercomes the force of the first mentioned means.

12. In a snap acting device, a first movable member and a second movablemember; a fixed support for the first movable member; an overcenterspring interconnecting the said movable members; an operating member; afulcrum for said second movable member carried by the operating member;a spring interconnecting the operating member and said first movablemember for actuating the first movable member to move the firstmentioned spring over dead center on movement of the operating member tocause snap action of the first and second movable members; and means foractuating the operating member.

13. In a snap acting device, a movable member; a snap member fulcrumedat a fixed point; elastic means cooperating with the movable member andthe snap member, said movable member having a dead center position withrespect to the elastic means and the snap member; an actuating member,said actuating member carrying said movable member; resilient meanscooperating with the snap member and the acresilient member for movingsaid element from one of the extreme positions to an opposite extremeposition including a second resilient member for urging the firstresilient member toward the second mentioned extreme position withrespect to the element; and means for reversing the directions of forceof the second resilient member on the first member for moving said firstmember in opposite directions.

15. In a snap acting device, an element movable between two positions,said element having a pivot; a resilient member connected to the elementfor biasing said element in either of said positions, said member beingmovable to a position on either side of a line through the pivot and thepoint of connection of the member and element; means, including a secondresilient member, for yieldingly moving the first resiiient member fromone side of the said line to the other; and means for increasing theyielding effect of the second resilient member on the first member formoving said first member.

16. In a snap acting device, a movable element having a pivot; a springconnected to the element and being movable to a position on either sideof a line through the pivot and the point of connection of the springand element for actuating the element; means for moving the spring,including, a member connected to the spring and biased in one directionby the spring, and a second spring connected to the member for biasingthe member in the opposite direction and means for moving the secondspring relative to, the member for increasing the biasing effect of thesecond spring whereby the member is moved in said opposite directionwith a snap movement and moving the first spring therewith.

17. In a snap acting device, a movable element; means for limitingmovement of the element between two positions; a translatable resilientmember connected to the element; means for limiting movement of theresilient member between two positions; means for translating theresilient member for causing said element to be moved from one of itspositions to the other, including, a second resilient member for urgingthe first mentioned resilient member from one of its said positions tothe other; and means for reversing the directions of force of the secondresilient member on the first member for moving the first member ineither direction.

18. In a snap acting device, a movable element having translatablepivot; stop means for limiting movement of the element in one direction;snap mechanism for moving the element from the stop means, including aspring and a movable member, said spring connecting the element and themember and being disposed so that the moment of force thereof is at anangle with respect to a line from the pivot to the stop means toyieldingly urge the element against the stop means; an actuating memberfor moving the pivot to increase the angle between the spring and thesaid line while the actuating member moves in one direction; and meansfor shifting the spring to a position in which the moment of forcethereof is opposite the pre-shifted position thereof for moving theelement away from the stop means, said shifting means comprising snapacting mechanism including said movable member actuated by the actuatingmember after said actuating member moves a predetermined distance insaid one direction.

19. In a snap acting device, a movable element; stop means for limitingmovement of the element between two opposite positions; a springconnected to the element, said spring being adapted to move the elementfrom one of said positions to the other; a second spring connected tothe element for yieldingly retaining the element in either of saidpositions; and means for actuating the first spring for overcoming theyielding effect of the second spring and move the element to theopposite position.

20. In a snap acting device, an element movable in two directions; astop limiting the movement of the element in one of said directions anda stop limiting the movement of the element in the other of saiddirections; means for moving said element from one stop to the otherwith a snap movement; and means cooperating with said means for movingone of said stops relative to the other stop prior to snap movement ofthe element in the said one direction for increasing the snap movementof the element in the one direction and for moving said stop relative tothe other stop prior to snap movement of the element in the said otherdirection by said snap means for decreasing the movement of the elementin said other direction.

21. In a snap acting device, a pivoted element movable about its pivotin two directions; a stop limiting movement of the element in onedirection and a stop limiting movement of the element in the other ofsaid directions; snap acting means actuatable for moving said elementfrom one stop to the other; and a member for actuating the snap actingmeans, said member being adapted to move one of said stops in said onedirection to increase the movement of said element by the snap actingmeans in said one direction and to move the said one stop in the saidother direction for decreasing the movement of the element by the snapacting means in said other direction.

22. In a snap acting device, a pivoted element movable in twodirections; a stop limiting movement of the element about its pivot inone of said directions; a movable actuating member, said member having apart for engaging said element for limiting movement of the element inthe other of said directions; and snap mechanism operated by movement ofsaid actuating member for moving said element to said limiting part andstop with a snap action.

23. In a snap acting device, a pivoted element movable in twodirections; stops limiting the extent of movement of the element in saiddirections; snap acting mechanism for actuating the movable element; andmeans for actuating the snap actuating mechanism in opposite directionsand for actuating one of said stops for moving the pivoted elementtoward the other stop when said means is operating the snap actingmechanism in a direction to move the element to said other stop.

24. In a snap acting device, a pivoted element movable in twodirections; stops limiting the extent of movement of the element in saiddirections; snap mechanism for actuating the movable element; a levercarrying one of said stops; and means intermediate the stop and fulcrumof said lever for actuating the snap mechanism.

PAUL B. LEONARD.

